The thermal conductivity of silicones is relatively poor with average values at 100°C 0.2-0.3 W.m¯¹.K¯¹. A product with poor temperature conduction is therefore a good isolator and hence silicone can often be used in environments where thermal isolation is not necessarily a priority. As silicone is one of the rubbers with the highest temperature capabilities it can therefore isolate in scenarios, where other rubbers would melt.
Special thermally conductive grades achieve values of 0.8-1.2 W.m¯¹.K¯¹. They can be used in scenarios where silicone is needed maybe due to height of the temperature in the process but where isolation for whatever reason is not appreciated. These products are commonly requested for scientific or laboratory environments.